/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package mj.ocraptor.extraction.tika.parser.txt;

import java.io.IOException;
import java.io.InputStream;
import java.nio.charset.Charset;
import java.util.Collections;
import java.util.Set;

import org.apache.tika.config.ServiceLoader;
import org.apache.tika.exception.TikaException;
import org.apache.tika.io.CloseShieldInputStream;
import org.apache.tika.metadata.Metadata;
import org.apache.tika.mime.MediaType;
import org.apache.tika.parser.AbstractParser;
import org.apache.tika.parser.ParseContext;
import org.apache.tika.sax.XHTMLContentHandler;
import org.xml.sax.ContentHandler;
import org.xml.sax.SAXException;

/**
 * Plain text parser. The text encoding of the document stream is automatically
 * detected based on the byte patterns found at the beginning of the stream and
 * the given document metadata, most notably the <code>charset</code> parameter
 * of a {@link org.apache.tika.metadata.HttpHeaders#CONTENT_TYPE} value.
 * <p>
 * This parser sets the following output metadata entries:
 * <dl>
 * <dt>{@link org.apache.tika.metadata.HttpHeaders#CONTENT_TYPE}</dt>
 * <dd><code>text/plain; charset=...</code></dd>
 * </dl>
 */
public class TXTParser extends AbstractParser {

  /** Serial version UID */
  private static final long serialVersionUID = -6656102320836888910L;

  private static final Set<MediaType> SUPPORTED_TYPES = Collections
      .singleton(MediaType.TEXT_PLAIN);

  private static final ServiceLoader LOADER = new ServiceLoader(
      TXTParser.class.getClassLoader());

  public Set<MediaType> getSupportedTypes(ParseContext context) {
    return SUPPORTED_TYPES;
  }

  public void parse(InputStream stream, ContentHandler handler,
      Metadata metadata, ParseContext context) throws IOException,
      SAXException, TikaException {
    // Automatically detect the character encoding
    AutoDetectReader reader = new AutoDetectReader(new CloseShieldInputStream(
        stream), metadata, context.get(ServiceLoader.class, LOADER));
    try {
      Charset charset = reader.getCharset();
      MediaType type = new MediaType(MediaType.TEXT_PLAIN, charset);
      metadata.set(Metadata.CONTENT_TYPE, type.toString());
      // deprecated, see TIKA-431
      metadata.set(Metadata.CONTENT_ENCODING, charset.name());

      XHTMLContentHandler xhtml = new XHTMLContentHandler(handler, metadata);
      xhtml.startDocument();

      xhtml.startElement("p");
      char[] buffer = new char[4096];
      int n = reader.read(buffer);
      while (n != -1) {
        xhtml.characters(buffer, 0, n);
        n = reader.read(buffer);
      }
      xhtml.endElement("p");

      xhtml.endDocument();
    } finally {
      reader.close();
    }
  }

}
